Evaluation of skin sensitization potential of UV filters by in vitro methods

Author(s)

Carolina Gomes Benevenuto Moreira

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Ciências Farmacêuticas de Ribeirão Preto (PCARP/BC)
• Defense date: 2017-02-24

Examining board members

Lorena Rigo Gaspar Cordeiro; André Rolim Baby; Fabiani Gai Frantz; Vânia Rodrigues Leite e Silva

• Advisor: Lorena Rigo Gaspar Cordeiro

Abstract

Allergic contact dermatitis is considered a complex disease and it is estimated that it reaches 15-20% of population. Among cosmetic ingredients, fragrances, preservatives and hair dyes are the most frequently cause of cosmetic allergy and UV filters can be considered emergent allergens. Traditionally, skin sensitization, the first step of allergic contact dermatitis, was assessed by animal testing, such as LLNA - Local lymph node assay. However, in the European Union the 7th Amendment to the Cosmetics Directive (Directive 20003/15/CE) resulted in the complete ban of animal testing for cosmetic products and ingredients in 2013. This legislation stimulated the development of many in vitro methods and OECD accepted the validation of three of them for sensitization. However, it is not possible to replace animal testing for skin sensitization assessment with only one in vitro method and there is no consensus about an integrated strategy for the identification of sensitizers. This way, the reconstructed skin models can represent a good option, once they allow the assessment of many steps of skin sensitization, as well as the assessment of lipophilic chemicals. Thus, the present study presents a great relevance, once it assessed skin sensitization of UV filters by in vitro methods. For this purpose, in the first step, the UV filters avobenzone and benzophenone-3 were submitted to the assessment of skin irritation in reconstructed skin models, by the quantification of the cell viability and the release of IL-1α. Then, the skin sensitization of these UV filters was assessed, including octocrylene, by the in chemico assay DPRA, through the depletion of the cysteine and lysine peptides, and also by the reconstructed skin models containing or not T cells, through the quantification of the cell viability and the release of IL-6, IL-8 and IL-18. Phototoxicity and Photosensitization were assessed after the exposure of the skin models to UVA radiation. Results showed that UV filters were not considered irritants nor sensitizers in the proposed methods. The assay involving the skin model with T cells with the release of IL-18 was considered the most suitable in the assessment of skin sensitization. Avobenzone was not considered phototoxic, however it was considered photosensitizer in the skin models. Finally, the present study has a great relevance and innovation, once it combines results obtained in alternative methods to animal testing for the assessment of skin sensitization, the assessment of its related endpoints, such as skin irritation and also photoinduced processes such as phototoxicity and photosensitization. The present study also presents new tools, such as the inclusion of T cells in skin models for the skin sensitization assessment as well as the skin models for skin photosensitization, which is frequently associated with monolayer cell culture assays. (AU)

• FAPESP's process: 13/01219-6 - Evaluation of allergenic potential of different raw materials and sunscreen formulations by in vitro and in vivo methods
• Grantee: Carolina Gomes Benevenuto Moreira
• Support Opportunities: Scholarships in Brazil - Doctorate